Interior lining parts having a cover layer which forms a decorative surface are known in the automobile industry. They are used for example as instrument panels, as door linings, as column linings or even as storage compartment covers.
It is the purpose of such components to combine desired mechanical properties with optical and even haptic properties. In order to achieve this, such a component is generally composed of a carrier which determines the mechanical properties, a foam layer which determines the haptic properties and a cover layer which determines essentially the optical properties. Components are also known which dispense with the mentioned additional foam layer, i.e. the skin is connected directly to the carrier.
Furthermore, it is known to compose covers layers from two or more skins.
However it is problematic in the case of multipart cover layers that, in the common boundary regions of the skins, foam or rear-sprayed material can emerge during rear-foaming or rear-spraying because of unsealed places and hence can reduce the quality of the surface.
A known method for foam-tight connection of skins is firstly to turn over the skins in the joint region and to sew them together in the turned-over region. The seam is then sealed in addition for the foaming process.
A further possibility for connecting skins together in a foam-tight manner is described in the publication DE 100 44 627 A1. According to the invention, two adjacent skins are connected to each other along the seam line thereof via a retaining means. In one embodiment, the retaining means is configured as a profile-like strip which clamps the adjacent skins together along the seam line. The skins connected to each other in a foam-tight manner in this way are inserted into the tool after connection with the retaining means and then are rear-foamed or rear-sprayed.
The disadvantage of these methods is that an additional method step and/or additional connection means must be used in order to connect the skins together.
The published patent specification JP 2002-052548 likewise discloses a method for the production of a component having a multipart cover layer. According to this method, two skins forming a cover layer are inserted in a tool half in such a manner that these overlap in their end regions. A rigid carrier which has a large number of adjacently disposed projections is disposed in the other tool half. The carrier is disposed thereby in such a manner that the projections protrude into the cavity. Upon closing the tool, the ends of the carrier come to be situated on the overlapping region of the skins and, in this way, press the overlapping region of the end regions of both skins together in portions. Thereafter, the cover layer is rear-foamed. By means of pressing the overlapping region together, the passage of foam is intended to be prevented during rear-foaming.
The disadvantage of this method or of this type of seal is that, on the one hand, the carrier is complex to produce because of the projections and, on the other hand, it increases in weight. Furthermore, these projections can be felt through the skins. Hence in this region, no uniform haptics are possible.